1. Field of the Invention
The present invention relates to devices for monitoring environmental characteristics, and in particular, to a network of devices for monitoring and reporting on environmental characteristics.
2. Description of the Related Art
As various forms of sensors have been developed to become smaller, more efficient and less expensive, it has become increasingly practical to develop and deploy systems for monitoring and reporting on various environmental conditions or characteristics. Such conditions or characteristics include, among others and without limitation, humidity, pressure, electromagnetic radiation, light, acceleration, various chemical concentrations, and temperature. Indeed, the range or types of conditions or characteristics that can be monitored are limited only by the sensors used to provide sufficient and suitable signals for the circuitry needed for processing the data represented by such signals.
For example, many products, particularly food products, require a controlled environment during some or all stages of production, shipping and handling, and sales. Particularly for food products, temperature is often the most critical environmental characteristic to be maintained. Food products must often be shipped for long distances to their final destination, with trips often taking several days, thereby requiring that the food be frozen or refrigerated during such trips. The freshness and safety of the food product depends upon proper maintenance of the temperature. This is particularly true for foods such as meat, fish and poultry, where even relatively small temperature excursions outside the desired range, for even only short durations, can be dangerous due to spoilage.
It is well known in the art for distributors of frozen and refrigerated foods to place temperature-sensitive elements (e.g., on adhesive strips) in or on the containers in which the food products are shipped. Such devices will indicate whether the shipping container has been allowed to rise above a threshold temperature at any point during the trip. However, nearly indicating whether such temperature threshold has been crossed, without any further information about the duration or timing of such temperature change is generally not sufficient to fully assess the effects of such temperature changes.
Accordingly, it would be desirable to have a system for monitoring and reporting on one or more characteristics, such as temperature, within a defined environment.